The O-pyridyl phosphates and phosphorothioates were described by Rigterink in U.S. Pat. No. 3,244,586. Such compounds are particularly useful as insecticides and biocides. They are represented by Formula (I) ##STR1## wherein R represents halopyridyl,
Z represents oxygen or sulfur and each R' independently represents lower alkyloxy, amino or lower alkylamino. PA1 each X independently represent bromo, chloro, fluoro, iodo, --NR.sup.2 R.sup.3 wherein R.sup.2 and R.sup.3 independently represent hydrogen and alkyl of 1 to 6 carbon atoms, cyano, nitro, alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkylthio of 1 to 6 carbon atoms or alkylsulfinyl of 1 to 6 carbon atoms; PA1 n is 0, 1, 2 or 3 with the proviso, that when n is more than one, all substituents are sterically compatible with each other; and PA1 Z is oxygen or sulfur. PA1 "steric hindrance. A characteristic of molecular structure in which the molecules have a spatial arrangement of their atoms such that a given reaction with another molecule is prevented or retarded in rate."
Rigterink disclosed several methods for preparing the compounds but his preferred method comprised reacting a phosphorochloridate or phosphorochloridothioate of Formula (II) ##STR2## with an alkali metal or tertiary amine salt of a halopyridinol having the formula R--O-alkali metal or R--OH tertiary amine. The disclosed methods were carried out in an inert organic liquid under anhydrous conditions. In each of the disclosed processes, an alkali metal chloride or the tertiary amine hydrochloride salt is produced as a reaction by-product which is removed by filtration. The disclosure of U.S. Pat. No. 3,244,586 is incorporated herein by reference.
Other phosphorothioates and phenylphosphonothioates have been similarly prepared and used. See, for example, U.S. Pat. Nos. 4,007,197 and 4,147,866 both of which teach the reaction of an alkali metal phenate, pyridinate or pyrimidinate with an O,O-dialkylphosphorochloridothioate or O-alkyl phenylphosphonochloridothioate under alkaline conditions in a liquid reaction medium and in the presence of a co-catalyst mixture of a quaternary ammonium or phosphonium salt and a tertiary amine.
U.S. Pat. No. 3,928,370 teaches the preparation of dialkyl pyridylphosphates by the reaction of an alkali metal pyridinate and a dialkyl hydrogen phosphite in the presence of a liquid reaction medium and in the presence of a tertiary amine catalyst.
Many other commercially available phosphorothioates and phosphates prepared by the same general procedure as set forth above are listed in articles by O. Johnson in Chemical Week, pages 10-46 (July 26, 1972), and by E.E. Kenaga and W. E. Allison in the Bulletin of the Entomological Society of America, Volume 15, No. 2, pages 85-148 (June 1969) which also list the U.S. Patent Numbers of many of said compounds. These articles are incorporated herein by reference thereto.